buildman: Add an option to check maintainers

Rather than using the -R option to get this report as a side effect, add
a dedicated option for it.

Disable CI for now as there are some missing maintainers, unfortunately.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/boards.py b/tools/buildman/boards.py
index e608f79..83adbf1 100644
--- a/tools/buildman/boards.py
+++ b/tools/buildman/boards.py
@@ -213,11 +213,13 @@
         if self._tmpfile:
             try_remove(self._tmpfile)
 
-    def scan(self, defconfig):
+    def scan(self, defconfig, warn_targets):
         """Load a defconfig file to obtain board parameters.
 
         Args:
             defconfig (str): path to the defconfig file to be processed
+            warn_targets (bool): True to warn about missing or duplicate
+                CONFIG_TARGET options
 
         Returns:
             tuple: dictionary of board parameters.  It has a form of:
@@ -252,19 +254,20 @@
                 params[key] = '-'
 
         # Check there is exactly one TARGET_xxx set
-        target = None
-        for name, sym in self._conf.syms.items():
-            if name.startswith('TARGET_') and sym.str_value == 'y':
-                tname = name[7:].lower()
-                if target:
-                    warnings.append(
-                        f'WARNING: {leaf}: Duplicate TARGET_xxx: {target} and {tname}')
-                else:
-                    target = tname
+        if warn_targets:
+            target = None
+            for name, sym in self._conf.syms.items():
+                if name.startswith('TARGET_') and sym.str_value == 'y':
+                    tname = name[7:].lower()
+                    if target:
+                        warnings.append(
+                            f'WARNING: {leaf}: Duplicate TARGET_xxx: {target} and {tname}')
+                    else:
+                        target = tname
 
-        if not target:
-            cfg_name = expect_target.replace('-', '_').upper()
-            warnings.append(f'WARNING: {leaf}: No TARGET_{cfg_name} enabled')
+            if not target:
+                cfg_name = expect_target.replace('-', '_').upper()
+                warnings.append(f'WARNING: {leaf}: No TARGET_{cfg_name} enabled')
 
         params['target'] = expect_target
 
@@ -666,7 +669,8 @@
         return result, warnings
 
     @classmethod
-    def scan_defconfigs_for_multiprocess(cls, srcdir, queue, defconfigs):
+    def scan_defconfigs_for_multiprocess(cls, srcdir, queue, defconfigs,
+                                         warn_targets):
         """Scan defconfig files and queue their board parameters
 
         This function is intended to be passed to multiprocessing.Process()
@@ -678,10 +682,12 @@
                 written into this.
             defconfigs (sequence of str): A sequence of defconfig files to be
                 scanned.
+            warn_targets (bool): True to warn about missing or duplicate
+                CONFIG_TARGET options
         """
         kconf_scanner = KconfigScanner(srcdir)
         for defconfig in defconfigs:
-            queue.put(kconf_scanner.scan(defconfig))
+            queue.put(kconf_scanner.scan(defconfig, warn_targets))
 
     @classmethod
     def read_queues(cls, queues, params_list, warnings):
@@ -698,7 +704,7 @@
                 params_list.append(params)
                 warnings.update(warn)
 
-    def scan_defconfigs(self, config_dir, srcdir, jobs=1):
+    def scan_defconfigs(self, config_dir, srcdir, jobs=1, warn_targets=False):
         """Collect board parameters for all defconfig files.
 
         This function invokes multiple processes for faster processing.
@@ -707,6 +713,8 @@
             config_dir (str): Directory containing the defconfig files
             srcdir (str): Directory containing source code (Kconfig files)
             jobs (int): The number of jobs to run simultaneously
+            warn_targets (bool): True to warn about missing or duplicate
+                CONFIG_TARGET options
 
         Returns:
             tuple:
@@ -732,7 +740,7 @@
             que = multiprocessing.Queue(maxsize=-1)
             proc = multiprocessing.Process(
                 target=self.scan_defconfigs_for_multiprocess,
-                args=(srcdir, que, defconfigs))
+                args=(srcdir, que, defconfigs, warn_targets))
             proc.start()
             processes.append(proc)
             queues.append(que)
@@ -819,7 +827,8 @@
         with open(output, 'w', encoding="utf-8") as outf:
             outf.write(COMMENT_BLOCK + '\n'.join(output_lines) + '\n')
 
-    def build_board_list(self, config_dir, srcdir, jobs=1):
+    def build_board_list(self, config_dir=CONFIG_DIR, srcdir='.', jobs=1,
+                         warn_targets=False):
         """Generate a board-database file
 
         This works by reading the Kconfig, then loading each board's defconfig
@@ -830,6 +839,8 @@
             config_dir (str): Directory containing the defconfig files
             srcdir (str): Directory containing source code (Kconfig files)
             jobs (int): The number of jobs to run simultaneously
+            warn_targets (bool): True to warn about missing or duplicate
+                CONFIG_TARGET options
 
         Returns:
             tuple:
@@ -839,7 +850,8 @@
                     value: string value of the key
                 list of str: Warnings that came up
         """
-        params_list, warnings = self.scan_defconfigs(config_dir, srcdir, jobs)
+        params_list, warnings = self.scan_defconfigs(config_dir, srcdir, jobs,
+                                                     warn_targets)
         m_warnings = self.insert_maintainers_info(srcdir, params_list)
         return params_list, warnings + m_warnings
 
diff --git a/tools/buildman/buildman.rst b/tools/buildman/buildman.rst
index 6808727..ebc552f 100644
--- a/tools/buildman/buildman.rst
+++ b/tools/buildman/buildman.rst
@@ -1311,6 +1311,19 @@
 since it may be dropped altogether in future.
 
 
+Checking maintainers
+--------------------
+
+Sometimes a board is added without a corresponding entry in a MAINTAINERS file.
+Use the `--maintainer-check` option to check this::
+
+   $ buildman --maintainer-check
+   WARNING: board/mikrotik/crs3xx-98dx3236/MAINTAINERS: missing defconfig ending at line 7
+   WARNING: no maintainers for 'clearfog_spi'
+
+Buildman returns with an exit code of 2 if there area any warnings.
+
+
 Checking the command
 --------------------
 
diff --git a/tools/buildman/cmdline.py b/tools/buildman/cmdline.py
index a9cda24..36acac5 100644
--- a/tools/buildman/cmdline.py
+++ b/tools/buildman/cmdline.py
@@ -85,6 +85,8 @@
     parser.add_option(
           '-M', '--allow-missing', action='store_true', default=False,
           help='Tell binman to allow missing blobs and generate fake ones as needed'),
+    parser.add_option('--maintainer-check', action='store_true',
+                      help='Check that maintainer entries exist for each board')
     parser.add_option(
           '--no-allow-missing', action='store_true', default=False,
           help='Disable telling binman to allow missing blobs'),
diff --git a/tools/buildman/control.py b/tools/buildman/control.py
index 09a11f2..fc9e926 100644
--- a/tools/buildman/control.py
+++ b/tools/buildman/control.py
@@ -202,6 +202,8 @@
             sys.exit(col.build(col.RED, '-w requires that you specify -o'))
         options.output_dir = '..'
 
+    nr_cups = options.threads or multiprocessing.cpu_count()
+
     # Work out what subset of the boards we are building
     if not brds:
         if not os.path.exists(options.output_dir):
@@ -209,8 +211,15 @@
         board_file = os.path.join(options.output_dir, 'boards.cfg')
 
         brds = boards.Boards()
-        ok = brds.ensure_board_list(board_file,
-                                    options.threads or multiprocessing.cpu_count(),
+        if options.maintainer_check:
+            warnings = brds.build_board_list(jobs=nr_cups)[1]
+            if warnings:
+                for warn in warnings:
+                    print(warn, file=sys.stderr)
+                return 2
+            return 0
+
+        ok = brds.ensure_board_list(board_file, nr_cups,
                                     force=options.regen_board_list,
                                     quiet=not options.verbose)
         if options.regen_board_list:
diff --git a/tools/buildman/func_test.py b/tools/buildman/func_test.py
index bb9eea3..7f3d54c 100644
--- a/tools/buildman/func_test.py
+++ b/tools/buildman/func_test.py
@@ -976,7 +976,8 @@
 endif
 ''')
         tools.write_file(kc_file, orig_kc_data + extra)
-        params_list, warnings = self._boards.build_board_list(config_dir, src)
+        params_list, warnings = self._boards.build_board_list(config_dir, src,
+                                                              warn_targets=True)
         self.assertEquals(2, len(params_list))
         self.assertEquals(
             ['WARNING: board2_defconfig: Duplicate TARGET_xxx: board2 and other'],
@@ -986,7 +987,8 @@
         lines = [b'' if line == b'config TARGET_BOARD2\n' else line
                   for line in orig_kc_data.splitlines(keepends=True)]
         tools.write_file(kc_file, b''.join(lines))
-        params_list, warnings = self._boards.build_board_list(config_dir, src)
+        params_list, warnings = self._boards.build_board_list(config_dir, src,
+                                                              warn_targets=True)
         self.assertEquals(2, len(params_list))
         self.assertEquals(
             ['WARNING: board2_defconfig: No TARGET_BOARD2 enabled'],